Stuka Bomber

Hey guys, so for the last couple days I've been getting the "Low coolant" warning but only in the morning.

I checked the reservoir and it's full. But I also now recieve the "Washer fluid Low" warning now too.

I've read that the washer fluid and the coolant level sensors are in series and that one or both of them can go and flash this warning.

Any truth to this? Is there a good DIY for replacing them? How about a good source for both sensors?

Do I need to drain the reservoirs before replacing the sensors?

Thanks guys.